vendredi 5 septembre 2014

NASA's ISS-RapidScat wind-watching scatterometer, which is scheduled to launch to the International Space Station no earlier than Sept. 19, will be the first science payload to be robotically assembled in space since the space station itself. This image shows the instrument assembly on the left, shrouded in white. On the right is Rapid-Scat's nadir adapter, a very sophisticated bracket that points the scatterometer toward Earth so that it can record the direction and speed of ocean winds. The two pieces are stowed in the unpressurized trunk of a SpaceX Dragon cargo spacecraft at Cape Canaveral Air Force Station in Florida.

A New Measure of Ocean Winds

Video above: A new tool for tracking hurricanes and tropical storms, ISS-RapidScat is the first instrument specifically created to watch Earth from the International Space Station.

Howard Eisen, the ISS-RapidScat project manager at NASA's Jet Propulsion Laboratory, Pasadena, California, said, "Another mission had the idea of a two-piece payload first, but we beat them to the punch." The RapidScat team designed and built both parts of the science payload in an 18-month-long sprint so as to take advantage of an available berthing space on the space station and a free ride on a resupply mission. The other two-piece payload is still a year and a half from launch.

Each piece of the ISS-RapidScat payload is attached to the space station by a standardized interface called a Flight Releasable Attachment Mechanism, or FRAM. JPL's Stacey Boland, an engineer on the ISS-RapidScat team, explained, "The space station is almost like a Lego system, and a FRAM is a particular type of Lego block. We had to build on two separate Lego blocks because each block can only hold a certain amount of cargo."

Eisen noted, "We are not only robotically assembled, we are robotically installed." When the Dragon spacecraft reaches the station, a robotic arm will grapple it and bring it to its docking port. Using a different end effector -- a mechanical hand -- the arm will first extract the nadir adapter from the trunk and install it on an external site on the Columbus module of the space station. The arm will then pluck the RapidScat instrument assembly from the trunk and attach it to the nadir adapter, completing the installation. Each of the two operations will take about six hours.

Image above: Artist's rendering of NASA's ISS-RapidScat instrument (inset), which will launch to the International Space Station in 2014 to measure ocean surface wind speed and direction and help improve weather forecasts, including hurricane monitoring. It will be installed on the end of the station's Columbus laboratory. Image credit: NASA/JPL-Caltech/JSC.

NASA monitors Earth's vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. NASA develops new ways to observe and study Earth's interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.

This new NASA/ESA Hubble Space Telescope image shows a beautiful spiral galaxy known as PGC 54493, located in the constellation of Serpens (The Serpent). This galaxy is part of a galaxy cluster that has been studied by astronomers exploring an intriguing phenomenon known as weak gravitational lensing.

This effect, caused by the uneven distribution of matter (including dark matter) throughout the Universe, has been explored via surveys such as the Hubble Medium Deep Survey. Dark matter is one of the great mysteries in cosmology. It behaves very differently from ordinary matter as it does not emit or absorb light or other forms of electromagnetic energy — hence the term "dark."

Even though we cannot observe dark matter directly, we know it exists.
One prominent piece of evidence for the existence of this mysterious
matter is known as the "galaxy rotation problem." Galaxies rotate at
such speeds and in such a way that ordinary matter alone — the stuff we
see — would not be able to hold them together. The amount of mass that
is "missing" visibly is dark matter, which is thought to make up some 27
percent of the total contents of the Universe, with dark energy and
normal matter making up the rest. PGC 55493 has been studied in
connection with an effect known as cosmic shearing. This is a weak
gravitational lensing effect that creates tiny distortions in images of
distant galaxies.

Hubble orbiting Earth

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington.

jeudi 4 septembre 2014

The most accurate and comprehensive collection of rain, snowfall and other types of precipitation data ever assembled now is available to the public. This new resource for climate studies, weather forecasting, and other applications is based on observations by the Global Precipitation Measurement (GPM) Core Observatory, a joint mission of NASA and the Japan Aerospace Exploration Agency (JAXA), with contributions from a constellation of international partner satellites.

Scanning a Snow Storm

Video Credit: Image Credit: NASA's Goddard Space Flight Center.

The GPM Core Observatory, launched from Japan on Feb. 27, carries two advanced instruments to measure rainfall, snowfall, ice and other precipitation. The advanced and precise data from the GPM Core Observatory are used to unify and standardize precipitation observations from other constellation satellites to produce the GPM mission data. These data are freely available through NASA's Precipitation Processing System at Goddard Space Flight Center in Greenbelt, Maryland.

"We are very pleased to make all these data available to scientists and other users within six months of launch," said Ramesh Kakar, GPM program scientist in the Earth Science Division at NASA Headquarters, Washington.

In addition to NASA and JAXA, the GPM mission includes satellites from the U.S. National Oceanic and Atmospheric Administration, U.S. Department of Defense's Defense Meteorological Satellite Program, European Organisation for the Exploitation of Meteorological Satellites, Indian Space Research Organisation, and France's Centre National d’Études Spatiales.

Instruments on the GPM Core Observatory and partner satellites measure energy naturally emitted by liquid and frozen precipitation. Scientists use computer programs to convert these data into estimates of rain and snowfall. The individual instruments on the partner satellites collect similar data, but the absolute numbers for precipitation observed over the same location may not be exactly the same. The GPM Core Observatory's data are used as a reference standard to smooth out the individual differences, like a principal violinist tuning the individual instruments in an orchestra. The result is data that are consistent with each other and can be meaningfully compared.
With the higher sensitivity to different types of precipitation made possible by the GPM Core Observatory's Microwave Imager (GMI) and Dual-frequency Precipitation Radar (DPR), scientists can for the first time accurately measure the full range of precipitation from heavy rain to light rain and snow. The instruments are designed not only to detect rain and snow in the clouds, but to measure the size and distribution of the rain particles and snowflakes. This information gives scientists a better estimate of water content and a new perspective on winter storms, especially near the poles where the majority of precipitation is snowfall.

Image above: One of the first storms observed by the NASA/JAXA GPM Core Observatory on March 17, 2014, in the eastern United States revealed a full range of precipitation, from rain to snow. Image Credit: NASA/JAXA.

"With this GPM mission data, we can now see snow in a way we could not before," said Gail Skofronick-Jackson, GPM project scientist at Goddard Space Flight Center. "Cloud tops high in the atmosphere have ice in them. If the Earth’s surface is above freezing, it melts into rain as it falls. But in some parts of the world, it's cold enough that the ice and snow falls all the way to the ground."

One of the first storms observed by the GPM Core Observatory on March 17 in the eastern United States showed that full range of precipitation. Heavy rains fell over the North and South Carolina coasts. As the storm moved northward, West Virginia, Virginia, Maryland and Washington were covered with snow. The GMI observed an 547 mile- (880 kilometer) wide track of precipitation on the surface, while the DPR imaged every 820 feet (250 meters) vertically to get the three-dimensional structure of the rain and snowfall layer by layer inside the clouds.

"What's really clear in these images is the melting layer, the place in the atmosphere where ice turns into rain," said Skofronick-Jackson. "The melting layer is one part of the precipitation process that scientists don’t know well because it is in such a narrow part of the cloud and changes quickly. Understanding the small scale details within the melting layer helps us better understand the precipitation process."

The combined snowfall and rainfall measurements from GPM will fill in the picture of where and how water moves throughout the global water cycle.

"Scientists and modelers can use the new GPM data for weather forecasts, estimating snowpack accumulation for freshwater resources, flood and landslide prediction, or tracking hurricanes," Skofronick-Jackson said. "This revolutionary information also gives us a better grasp of how storms and precipitating systems form and evolve around the planet, providing climate modelers insight into how precipitation might change in a changing climate."

GPM data are freely available to registered users from Goddard's Precipitation Processing System (PPS) website. The data sets are currently available in strips called swaths that correspond to the satellites' overpasses. Daily and monthly, global maps are also available from all the sensors. In the coming months, the PPS will merge this instrument data from all partner satellites and the Core Observatory into a seamless map that shows global rain and snow data at a 6-mile (10-kilometer) resolution every 30 minutes.

The GPM Core Observatory was the first of five scheduled NASA Earth science missions launching within a year. NASA monitors Earth's vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. NASA also develops new ways to observe and study Earth's interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. The agency freely shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.

A small asteroid, designated 2014 RC, will safely pass very close to Earth on Sunday, Sept. 7, 2014. At the time of closest approach, based on current calculations to be about 2:18 p.m. EDT (11:18 a.m. PDT / 18:18 UTC), the asteroid will be roughly over New Zealand. From its reflected brightness, astronomers estimate that the asteroid is about 60 feet (20 meters) in size.

Graphic above: This graphic depicts the passage of asteroid 2014 RC past Earth on September 7, 2014. At time of closest approach, the space rock will be about one-tenth the distance from Earth to the moon. Times indicated on the graphic are Universal Time. Image Credit: NASA/JPL-Caltech.

Asteroid 2014 RC was initially discovered on the night of August 31 by the Catalina Sky Survey near Tucson, Arizona, and independently detected the next night by the Pan-STARRS 1 telescope, located on the summit of Haleakalā on Maui, Hawaii. Both reported their observations to the Minor Planet Center in Cambridge, Massachusetts. Additional follow-up observations by the Catalina Sky Survey and the University of Hawaii 88-inch (2.2-meter) telescope on Mauna Kea confirmed the orbit of 2014 RC.

At the time of closest approach, 2014 RC will be approximately one-tenth the distance from the center of Earth to the moon, or about 25,000 miles (40,000 kilometers). The asteroid's apparent magnitude at that time will be about 11.5, rendering it unobservable to the unaided eye. However, amateur astronomers with small telescopes might glimpse the fast-moving appearance of this near-Earth asteroid.

Graphic above: This graphic depicts the orbit of asteroid 2014 RC around the sun. A house-sized asteroid will safely fly past Earth Sunday afternoon, September 7, at a distance equivalent to about one-tenth of the distance between Earth and the moon. Image Credit: NASA/JPL-Caltech.

The asteroid will pass below Earth and the geosynchronous ring of communications and weather satellites orbiting about 22,000 miles (36,000 kilometers) above our planet’s surface. While this celestial object does not appear to pose any threat to Earth or satellites, its close approach creates a unique opportunity for researchers to observe and learn more about asteroids.

While 2014 RC will not impact Earth, its orbit will bring it back to our planet's neighborhood in the future. The asteroid's future motion will be closely monitored, but no future threatening Earth encounters have been identified.

mercredi 3 septembre 2014

One of the most visible signs of climate change in recent years was not even visible at all until a few decades ago.

The sea ice cap that covers the Arctic Ocean has been changing dramatically, especially in the last 15 years. Its ice is thinner and more vulnerable – and at its summer minimum now covers more than 1 million fewer square miles than in the late 1970s. That’s enough missing ice to cover Alaska, California and Texas.

A key part of the story of how the world was able to witness and document this change centers on meticulous work over decades by a small group of scientists at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Late nights in mainframe rooms, double- and triple-checking computer printouts, processing and re-processing data – until the first-ever accurate atlases of the world’s sea ice were published.

“Sea ice was one of the least understood variables in the Earth system,” said Claire Parkinson, a climate change senior scientist at NASA Goddard. “Thanks to satellites, now sea ice is one of the best studied components of the planet.”

A Selective History of Sea Ice Observations

Video above: Arctic sea ice has been been the last frontier of the North for thousands of years, testing the mettle of explorers and providing a way of life for people circling the top of the world. This animated timeline provides a quick ride from the days of early Greek exploration to the dawn of the Space Age. Image Credit: NASA/Goddard Space Flight Center.

Getting off the Ground

In the early 1970s, NASA was reaping accolades for putting men on the moon. The Apollo program was still up and running, and moonwalking astronauts were NASA’s face to the world.

But in lesser-known corners of the agency, scientists were laying the foundation for the modern era of using space as a means to look back at Earth. A few scientists thought they could use this vantage point to map the previously unmappable – the sea ice surrounding Antarctica and covering the Arctic Ocean.

“NASA was anxious to determine how much could be learned about the Earth from the new perspective provided by satellites,” Parkinson said, “and sea ice was one of the important climate variables being examined.”

Sea ice is always changing – pushed and pulled by winds and ocean currents, melting and freezing depending on the season. And unless you get above it – with a satellite – it’s nearly impossible to see at once how much area it covers, the shape it takes and its seasonal variations.

The first satellites to take a peek at the sea ice cover had been the multi-agency Television Infrared Observation Satellite (TIROS) weather satellites launched by NASA and others in the 1960s. But these spacecraft had only visible and infrared sensors. Thick cloud cover and the long, dark Arctic winter limited their ability to provide continuous sea ice coverage.

To solve this problem, scientists at NASA Goddard had developed a prototype instrument capable of recording the naturally occurring microwave radiation that comes from objects on the Earth’s surface and the atmosphere. To this instrument, clouds were not obstacles and daylight was not necessary.

A series of aircraft research flights in 1967 and 1970 demonstrated its potential. The flights over Arctic sea ice in a NASA aircraft showed the strong contrast between the ice-free ocean and sea ice when observed at microwave wavelengths.

The instrument, the Electrically Scanning Microwave Radiometer (ESMR), launched into space aboard the Nimbus 5 satellite on December 10, 1972.

The game was changed, according to Don Cavalieri, a senior research sea ice scientist at NASA Goddard who led some later testing and validation airborne campaigns starting in the 1980s. The Goddard scientists could now calculate estimated sea ice concentrations within each 18.6-mile (30-kilometer) pixel of the satellite images.

“With satellites, it was the first time we got a global view of what’s happening with the sea ice cover,” Cavalieri said. “We saw that there were not only seasonal variations, but large interannual variations as well.”

Making Sense of the Data

But, while data on sea ice extent were now flowing from space to Earth, the scientists’ work had just begun. The early-era satellite instrument and limited computing power of the day provided plenty of challenges for the Goddard scientists before they could produce accurate sea ice maps.

Some of the images ESMR provided were sharp. Others had “fuzzy” pixels or obviously flawed radiation data, recalled Jay Zwally, a senior scientist at Goddard. In 1974, Zwally, a physicist who had been Program Manager for Glaciology and Remote Sensing at the National Science Foundation, came to NASA’s Goddard campus attracted by the potential he saw in ESMR for year-round, global observations of sea ice.

“We never found the cause of the intermittent glitch – there was speculation that maybe there was a little piece of solder inside the instrument that would occasionally short out something, which would cause the data to be uncalibrated,” Zwally said.

The microwave radiometer also had a geolocation problem – at times it would stick a segment of data in the wrong place. Scientists found and removed the misplaced and flawed data. In 1977 Zwally recruited Josefino Comiso, a physics-trained scientist, to process ESMR data. Comiso described the process as “painstaking. Because it could not be done digitally – it had to be done manually.”

Scientists used a mainframe computer and all the data were kept on 12-track tapes. There was only one of these million-dollar computers on the Goddard campus, which processed all the data from all the satellites in orbit controlled by the center.

“You had to sign up to use the computer, and sometimes you’d get a time slot in the middle of the night,” Comiso said.

To look at the microwave data, the scientists would first produce 18-inch paper printouts. Zwally wrote a program to delineate the ice edge and sea ice concentrations. From there, the researchers created tapes with the data that would be read by a film recorder called a Dicomed, which produced Polaroid images of sea ice.

“We then looked at the images and would recognize when data didn’t belong in there – erroneous data would just stand out,” Comiso said. “For example, we knew that in Antarctica the sea ice goes around the continent and the ice edge is continuous, so if there was a pattern that disrupted the ice edge, we’d know for sure it was wrong data.”

Images above: Arctic sea ice comparison for years 1979 and 1999. After two decades of observing Arctic sea ice from space, scientists in the late 1990s began to see enough change that they could quantify a downward trend in the size of the summer ice cover. Image Credit: NASA.

Atlases of Sea Ice

After years of meticulous work, Zwally, Comiso, Parkinson, Cavalieri and colleagues Per Gloersen, Bill Campbell, and Frank Carsey published the ESMR images in two atlases of sea ice. An Antarctic atlas led by Zwally was published in 1983, an Arctic atlas led by Parkinson in 1987.

They were the first of their kind ever published.

“The Soviets were so impressed that they translated them into Russian, reproducing our color pictures,” Comiso said.

Seelye Martin – now a professor emeritus of oceanography at University of Washington – remembers that the atlases made an impact.

“The ESMR atlases got a lot of attention because this was the first collection ever of monthly sea ice images that actually showed not only the ice edge – which people had known from ships and aircraft – but also the ice interior,” Martin said.

The monthly images showed how polar sea ice varies with the seasons and years. This kind of data is now converted to digital maps immediately and is available widely on the Internet. That was not the case in the late 1980s.

“Ships traveling in the Arctic and Antarctic would take these books with them, because nobody had ever shown them such detail regarding what to expect in which months and what kind of variability you can have from one year to another,” Parkinson said. “Now it’s very different, as now someone on a ship can get satellite data delivered to his or her computer within hours of when the data are collected.”

Toward the Modern Era

On October 24, 1978, NASA’s Nimbus 7 satellite launched carrying the Scanning Multichannel Microwave Radiometer (SMMR). Compared to ESMR, SMMR’s 10 channels allowed scientists to distinguish young ice that had recently formed from thicker and older ice that had been around for several years.

But Martin recalls that SMMR had its own suite of problems. “There was a lot of cross-talk between channels and it had a peculiar way of scanning,” said Martin, who worked with SMMR data. These shortcomings would get solved in the next generation of sea ice instruments, the Special Sensor Microwave/Imager (SSM/I), a microwave radiometer system flown on board satellites of the United States Air Force Defense Meteorological Satellite Program. SSM/Is have been operating almost continuously since June 1987.

NASA was tasked with the development work, then after a satellite technology was tested and seen to be of value, it would be handed to NOAA or the Department of Defense for long-term operations, Parkinson said.

“By the launch of SSM/I, it was a lot easier to work with the satellite data. The algorithms had finally settled down and been validated, plus people had desktop computers so the analysis was much easier,” Martin said. “It would be fair to say that most of the groundwork was done with ESMR and SMMR, and that SSM/I only required making some adjustments.”

Unlike the Nimbus 5 and Nimbus 7 missions, separated by a gap of over two years, SSM/I and SMMR overlapped in space for a few months, allowing researchers to compare and calibrate their datasets and create a nearly uninterrupted sea ice record starting in November 1978.

Cavalieri, Zwally, Comiso and Parkinson are still active at Goddard today. Algorithms authored by the Goddard scientists remain among the most widely used to detect sea ice coverage from satellite-based microwave instruments. Comiso is one of the coordinating lead authors on the cryosphere chapter of the U.N.’s Intergovernmental Panel on Climate Change Fifth Assessment Report, and all four of the scientists have served on relevant national and international committees.

The goal of establishing how to measure and record the changing extent of sea ice in both polar regions was largely accomplished by the end of the 1980s. But in the following years -- as it became clear that sea ice in the Arctic was undergoing fundamental changes -- this newly established record would become far more important than a simple a tool for ship navigators. Scientists were in for a big surprise.

Biomedical research and preparations for the departure of three crew members were the focus of activities Wednesday aboard the International Space Station as the six Expedition 40 astronauts and cosmonauts head into their final week together in space.

Commander Steve Swanson of NASA and his team of five flight engineers began the day with the usual 2 a.m. EDT reveille followed by a daily planning conference with the flight control teams around the world.

Afterward, Swanson downloaded the data from acoustic dosimeters that he and cosmonaut Max Suraev wore for the previous 24 hours. Swanson then swapped out the batteries and handed off the dosimeters to European Space Agency (ESA) astronaut Alexander Gerst and cosmonaut Oleg Artemyev for another 24-hour data collection period to help spacecraft designers learn more about the sound levels the crew is exposed to throughout the day.

Image above: Expedition 40 crew members pose for an in-flight crew portrait in the Harmony node of the International Space Station. Image Credit: NASA.

With an eye toward the end of his long-duration stay in space, Swanson spent some time packing up his remaining crew provisions, with some of the items slated to be loaded into the Soyuz TMA-12M spacecraft that will return Swanson, Artemyev and Soyuz Commander Alexander Skvortsov to Earth next week. The trio will undock their Soyuz from the Poisk module on the space-facing side of the station on Sept. 10 at 7:02 p.m. for a parachute-assisted landing in the steppe of Kazakhstan less than 3 ½-hours later.

Skvortsov spent much of the morning stowing items in the Soyuz, while Suraev and Artemyev recharged the satellite phone that will be carried aboard the returning Russian spacecraft.

Artemyev then moved on to some experiment work, including the SPLANH study which takes a look at the effects of spaceflight on the digestive system. Skvortsov meanwhile set up a portable HD camera inside the Soyuz to record the descent.

NASA astronaut Reid Wiseman began the day with an exercise session on the COLBERT treadmill while wearing medical monitors for the Sprint VO2Max study. The Sprint portion of the experiment measures the effectiveness of high-intensity, low-volume exercise training in minimizing the loss of muscle mass and bone density that occurs during spaceflight, while the VO2Max add-on takes a look at changes in aerobic capacity of people working in a closed environment.

While Wiseman worked out, Gerst spent the morning relaxing for science. The German astronaut donned a breathing mask and remained as relaxed as possible to allow for the most precise readings of his oxygen uptake for the ENERGY experiment. In an effort to contribute to crew health and performance as well as to ensure that crew members are getting the proper amount of food and exercise, researchers are measuring how much energy astronauts use during their space missions and tracking changes in their energy balance.

Wiseman rounded out his morning collecting water samples for the Microbiome study, which takes a look at the impact of space travel on the human immune system and an individual’s microbiome -- the collective community of microorganisms that are normally present in and on the human body.

Wiseman and Swanson then collected water and surface samples throughout the station to check for signs of microbial contamination. After a one-hour lunch break, Swanson analyzed the water samples.

Wiseman took a break from his work to talk with students in Evansville, Indiana, over the station’s ham radio. He then performed a scheduled inspection of the Advanced Resistive Exercise Device, or ARED, before working out on that weightlifting machine.

Image above: Flight Engineer Reid Wiseman sticks his head out of one of the crew quarters while Commander Steve Swanson works in front of a laptop computer aboard the International Space Station. Image Credit: NASA TV.

Next, Wiseman performed some routine maintenance on the Waste and Hygiene Compartment – the station’s toilet located in the Tranquility node. He wrapped up his workday charging batteries for a smartphone mapping experiment Swanson will conduct Thursday using one of the station’s soccer-ball-sized, free-flying robots known as the Synchronized Position Hold, Engage, Reorient, Experimental Satellites, or SPHERES.

Meanwhile, Skvortsov and Artemyev participated in a Soyuz descent training session to review their activities for next week’s departure. Their colleague Suraev conducted a photo survey of the panels inside the Zvezda service module.

After Gerst downloaded the data from his ENERGY relaxation session, he spent the remainder of the day working out on the station’s exercise bike and ARED to get in his daily exercise quota. Each crew member spends around 2 ½-hours every day working out to prevent the loss of bone density and muscle mass that occurs during long-duration spaceflight.

Approximately every 11 years, the sun undergoes a complete personality change from quiet and calm to violently active. The height of the sun’s activity, known as solar maximum, is a time of numerous sunspots, punctuated with profound eruptions that send radiation and solar particles out into the far reaches of space.

Image above: A composite of 25 separate images from NASA's SDO, spanning one year from April 2012 to April 2013. The image reveals the migration tracks of active regions towards the equator during that period. Image Credit: NASA/SDO/Goddard.

However, the timing of the solar cycle is far from precise. Since humans began regularly recording sunspots in the 17th century, the time between successive solar maxima has been as short as nine years, but as long as 14, making it hard to determine its cause. Now, researchers have discovered a new marker to track the course of the solar cycle—brightpoints, little bright spots in the solar atmosphere that allow us to observe the constant roiling of material inside the sun. These markers provide a new way to watch the way the magnetic fields evolve and move through our closest star. They also show that a substantial adjustment to established theories about what drives this mysterious cycle may be needed.

Historically, theories about what's going on inside the sun to drive the solar cycle have relied on only one set of observations: the detection of sunspots, a data record that goes back centuries. Over the past few decades, realizing that sunspots are areas of intense magnetic fields, researchers have also been able to include observations of magnetic measurements of the sun from more than 90 million miles away.

"Sunspots have been the perennial marker for understanding the mechanisms that rule the sun's interior," said Scott McIntosh, a space scientist at the National Center for Atmospheric Research in Boulder, Colorado, and first author of a paper on these results that appears in the September 1, 2014, issue of the Astrophysical Journal. "But the processes that make sunspots are not well understood, and far less, those that govern their migration and what drives their movement. Now we can see there are bright points in the solar atmosphere, which act like buoys anchored to what's going on much deeper down. They help us develop a different picture of the interior of the sun."

Solar Dynamics Observatory (SDO). Image Credit: NASA/Goddard

Over the course of a solar cycle, the sunspots tend to migrate progressively lower in latitude, moving toward the equator. The prevailing theory is that two symmetrical, grand loops of material in each solar hemisphere, like huge conveyor belts, sweep from the poles to the equator where they sink deeper down into the sun and then make their way steadily back to the poles. These conveyor belts also move the magnetic field through the churning solar atmosphere. The theory suggests that sunspots move in synch with this flow – tracking sunspots has allowed a study of that flow and theories about the solar cycle have developed based on that progression. But there is much that remains unknown: Why do the sunspots only appear lower than about 30 degrees? What causes the sunspots of consecutive cycles to abruptly flip magnetic polarity from positive to negative, or vice versa? Why is the timing of the cycle so variable?

Beginning in 2010, McIntosh and his colleagues began tracking the size of different magnetically balanced areas on the sun, that is, areas where there are an equal number of magnetic fields pointing down into the sun as pointing out. The team found magnetic parcels in sizes that had been seen before, but also spotted much larger parcels than those previously noted -- about the diameter of Jupiter. The researchers also looked at these regions in imagery of the sun's atmosphere, the corona, captured by NASA’s Solar Dynamics Observatory, or SDO. They noticed that ubiquitous spots of extreme ultraviolet and X-ray light, known as brightpoints, prefer to hover around the vertices of these large areas, dubbed “g-nodes” because of their giant scale.

These brightpoints and g-nodes, therefore, open up a whole new way to track how material flows inside the sun. McIntosh and his colleagues then collected information about the movement of these features over the past 18 years of available observations from the joint European Space Agency and NASA Solar and Heliospheric Observatory and SDO to monitor how the last solar cycle progressed and the current one started. They found that bands of these markers – and therefore the corresponding large magnetic fields underneath – also moved steadily toward the equator over time, along the same path as sunspots, but beginning at a latitude of about 55 degrees. In addition, each hemisphere of the sun usually has more than one of these bands present.

Solar Cycle: Magnetized March to Equator

Video above: Bands of magnetized solar material – with alternating south and north polarity – march toward the sun's equator. Comparing the evolution of the bands with the sunspot number in each hemisphere over time may change the way we think about what's driving the sun's 11-year sunspot cycle. Video Credit: S. McIntosh.

McIntosh explains that a complex interaction of magnetic field lines may take place in the sun’s interior that is largely hidden from view. The recent observations suggest that the sun is populated with bands of differently polarized magnetic material that, once they form, steadily move toward the equator from high latitudes. These bands will either have a northern or southern magnetic polarity and their sign alternates in each hemisphere such that the polarities always cancel. For example, looking at the sun’s northern hemisphere, the band closest to the equator – perhaps of northern polarity – would have magnetic field lines that connect it to another band, at higher latitudes, of southern polarity. Across the equator, in the bottom half of the sun, a similar process occurs, but the bands would be an almost mirror image of those across the equator, southern polarity near the equator and northern at higher latitudes. Magnetic field lines would connect the four bands; inside each hemisphere and across the equator as well.

While the field lines remain relatively short like this, the sun's magnetic system is calmer, producing fewer sunspots and fewer eruptions. This is solar minimum. But once the two low-latitude marching bands reach the equator their polarities essentially cancel each other out. Abruptly they disappear. This process, from migratory start to finish at the equator takes 19 years on average, but is seen to vary from 16 to about 21 years.

Following the equatorial battle and cancellation, the sun is left with just two large bands that have migrated to about 30 degrees latitude. The magnetic field lines from these bands are much longer and so the bands in each hemisphere feel less of each other. At this point, the sunspots begin to grow rapidly on the bands, beginning the ramp-up to solar max. The growth only lasts so long, however, because the process of generating a new band of opposite polarity has already begun at high latitudes. When that new band begins to appear, the complex four-band connection starts over and the number of sunspots starts to decrease on the low-latitude bands.

In this scenario, it is the magnetic band’s cycle – the lifetime of each band as it marches toward the equator – that truly defines the entire solar cycle. “Thus, the 11-year solar cycle can be viewed as the overlap between two much longer cycles,” said Robert Leamon, co-author on the paper at Montana State University in Bozeman and NASA Headquarters in Washington.

The new conceptual model also provides an explanation of why sunspots are trapped below 30 degrees and abruptly change sign. However, the model creates a question about a different latitude line: Why do the magnetic markers, the brightpoints and g-nodes, start appearing at 55 degrees?

"Above that latitude, the solar atmosphere appears to be disconnected from the rotation beneath it," said McIntosh. "So there is reason to believe that, inside the sun, there's a very different internal motion and evolution at high latitudes compared to the region near the equator. 55-degrees seems to be a critical latitude for the sun and something we need to explore further."

Solar cycles theories are best tested by making predictions as to when we will see the next solar minimum and the next solar maximum. This research paper forecasts that the sun will enter solar minimum somewhere in the last half of 2017, with the sunspots of the next cycle appearing near the end of 2019.

"People make their predictions for when this solar cycle will end and the next one will start," said Leamon. "Sometime in 2019 or 2020, some people will be proved right and others wrong."

In the meantime, regardless of whether the new hypothesis provided by McIntosh and his colleagues is correct, this long term set of bright points and g-node locations offers a new set of observations to explore the drivers of solar activity beyond only sunspots. Inserting this information into solar models will provide an opportunity to improve simulations of our star. Such advanced models tell us more about other stars too, leading to a better understanding of similar magnetic activity on more exotic, distant celestial counterparts.

Lupus 4, a spider-shaped blob of gas and dust, blots out background stars like a dark cloud on a moonless night in this intriguing new image. Although gloomy for now, dense pockets of material within clouds such as Lupus 4 are where new stars form and where they will later burst into radiant life. The Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile captured this new picture.

Lupus 4 is located about 400 light-years away from Earth, straddling the constellations of Lupus (The Wolf) and Norma (The Carpenter's Square). The cloud is one of several affiliated dark clouds found in a loose star cluster called the Scorpius–Centaurus OB association. An OB association is a relatively young, yet widely dispersed grouping of stars [1]. The stars likely had a common origin in a gigantic cloud of material.

The location of the Lupus 4 dark cloud in the constellation of Lupus

Because the association, and its Lupus clouds, form the closest such grouping to the Sun, they are a prime target for studying how stars grow up together before going their separate ways. The Sun, along with most stars in our galaxy, is thought to have started out in a similar environment.

American astronomer Edward Emerson Barnard is credited with the earliest descriptions of the Lupus dark clouds in the astronomical literature, back in 1927. Lupus 3, neighbour to Lupus 4, is the best studied, thanks to the presence of at least 40 fledgling stars formed over the last three million years, and which are on the cusp of igniting their fusion furnaces (eso1303). The main energy source in these adolescent stars, known as T Tauri stars, is the heat generated by their gravitational contraction. That is in contrast to the fusion of hydrogen and other elements which powers mature stars such as the Sun.

Wide-field view of the sky around the dark cloud Lupus 4

Observations of the cold darkness of Lupus 4 have turned up only a few T Tauri stars. Yet promisingly for Lupus 4 in terms of future star formation is a dense, starless core of material in the cloud. Given a few million years, that core should develop into T Tauri stars. Comparing Lupus 3 and Lupus 4 in this way suggests that the former is older than the latter, because its contents have had more time to develop into stars.

Zooming in on the dark cloud Lupus 4

How many stars might eventually start to shine within Lupus 4? It is hard to say, as mass estimates for Lupus 4 vary. Two studies agree on a figure of around 250 times the mass of the Sun, though another, using a different method, arrives at a figure of around 1600 solar masses. Either way, the cloud contains ample material to give rise to plenty of bright new stars. Rather as earthly clouds make way for sunshine, so, too, shall this cosmic dark cloud eventually dissipate and give way to brilliant starlight.

A close-up view of the dark cloud Lupus 4

Notes:

[1] The "OB" refers to the hot, bright, short-lived stars of spectral types O and B that are still shining brilliantly within the widely dispersed cluster as it travels through the Milky Way galaxy.

More information:

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning the 39-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

mardi 2 septembre 2014

Expedition 40 Commander Steve Swanson of NASA and his team of five flight engineers tackled a range of science experiments and supported an upgrade of the International Space Station’s computers Tuesday, all while preparing for next week’s journey back to Earth for half of the crew after nearly six months in space.

Swanson began the workday by setting up some acoustic dosimeters that he and cosmonaut Max Suraev will wear to track the noise levels they are exposed to for the next 24 hours.

The commander then moved on to the Skin B study as he tested the skin on his forearm with several dermatology tools. Skin B investigates the accelerated aging of skin that seems to occur during spaceflight. Results from this study will improve the understanding of the mechanisms of skin aging as well as provide insight into the aging process of similar body tissues.

Afterward, Swanson joined cosmonauts Alexander Skvortsov and Oleg Artemyev in their Soyuz TMA-12M spacecraft docked to the Poisk Mini-Research Module-2 to conduct leak checks of the Sokol launch and entry suits that the three will wear for the return to Earth. Swanson, Skvortsov and Artemyev are slated to undock from the station on Sept. 10 at 7:02 p.m. EDT for a parachute-assisted landing in the steppe of Kazakhstan less than 3 ½-hours later. They have been aboard the station since March 27.

With an eye toward the departure, Skvortsov and Artemyev also spent some time in the morning conducting some preliminary Lower Body Negative Pressure training. The two cosmonauts took turns donning a special outfit that simulates the effects of gravity by drawing fluids to the lower half of the body. In addition to conditioning cosmonauts for the return home, this device provides Russian researchers with data to predict how the cosmonauts will react to the full force of Earth’s gravity at the end of their mission.

NASA astronaut Reid Wiseman started his day by transferring some images from the latest session of the Canadian version of the Binary Colloidal Alloy Test, or BCAT-C1, and stowing the hardware. Results from this investigation of colloids – mixtures of small particles distributed throughout a liquid – will help materials scientists to develop new consumer products with unique properties and longer shelf lives.

Image above: Flight Engineer Reid Wiseman works with the Binary Colloidal Alloy Test experiment in the Kibo laboratory of the International Space Station. Image Credit: NASA.

Afterward, Wiseman unpacked some new pre-loaded hard drives from the European Space Agency’s fifth and final Automated Transfer Vehicle (ATV-5) and installed them in several portable computer system laptops. The ground team then initiated the transition of the station’s command and control computers.

Suraev meanwhile initialized some Matryoshka bubble dosimeters and handed them off to European Space Agency astronaut Alexander Gerst, who deployed them in the Harmony node to characterize the radiation environment aboard the station for the RaDI-N study.

Afterward, Gerst talked with reporters from RTL-TV in Cologne, Germany, to provide viewers in his home country with an update on the mission.

Gerst's interview with German media

Following a break for lunch, Swanson set up the Portable Pulmonary Function System hardware for the Sprint VO2max sessions that he and Wiseman will conduct this week. The Sprint experiment measures the effectiveness of high-intensity, low-volume exercise training in minimizing the loss of muscle mass and bone density that occurs during spaceflight. Station crew members currently work out around 2 ½-hours every day, and the Sprint team is looking into ways to reduce that total exercise time while maintaining crew fitness.

During the setup of the Sprint hardware, a 50-second delay was added to the communication link between Swanson and the ground team. The Communications Delay Assessment experiment simulates the lag in communications that will exist between Earth and a vehicle on a deep space mission.

Wiseman meanwhile continued swapping out hard drives for the computer system upgrades and setting up hardware for another colloid experiment, the Binary Colloidal Alloy Test-Kinetics Platform.

Wiseman and Swanson took a break from their work to talk with students gathered at the INFINITY Science Center, which is the visitor center associated with NASA’s Stennis Space Center in Mississippi.

Gerst rounded out his day setting up an armband monitor and other hardware for the ENERGY experiment in which he will be participating this week. In an effort to contribute to crew health and performance as well as to ensure that crew members are getting the proper amount of food and exercise, researchers are measuring how much energy astronauts use during their space missions and tracking changes in their energy balance.

Meanwhile on the Russian side of the complex, Suraev focused on routine activities including the daily maintenance of the life support system in the Zvezda service module.

Skvortsov and Artemyev spent their afternoon drying out and stowing the Sokol suits and gloves that they and Swanson wore earlier. They also pre-packed items for return to Earth aboard their Soyuz.

The international Cassini mission has revealed hundreds of lakes and seas spread across the icy surface of Saturn's moon Titan, mostly in its polar regions. These lakes are filled not with water but with hydrocarbons, a form of organic compound that is also found naturally on Earth and includes methane. While most of the liquid in the lakes is thought to be replenished by rainfall from clouds in the moon's atmosphere, the cycling of liquid throughout Titan's crust and atmosphere is still not well understood.

Titan's subsurface reservoirs. Credit: ESA/ATG medialab

A recent study led by Olivier Mousis at the Université de Franche-Comté, France, and involving colleagues at Cornell University and NASA's Jet Propulsion Laboratory in the USA, probed the hydrological cycle of Titan by examining how Titan's methane rainfall would interact with icy materials within underground reservoirs. They found that the formation of materials called clathrates changes the chemical composition of the rainfall runoff that fills these hydrocarbon reservoirs, leading to the formation of reservoirs of propane and ethane that may feed into some rivers and lakes.

"We knew that a significant fraction of the lakes on Titan's surface might be connected with hidden bodies of liquid beneath Titan's crust, but we just didn't know how they would interact", says Mousis. "Now, we've modelled the moon's interior in great detail, and have a better idea of what these hidden lakes or oceans could be like."

Mousis and colleagues modelled how a subsurface reservoir of liquid hydrocarbons would diffuse throughout Titan's porous icy crust. They found that this diffusion could cause a new reservoir – formed from clathrates - to form where the bottom of the original reservoir meets layers of non-porous ice.

Clathrates are compounds in which water forms a crystal structure with small cages that trap other substances like methane and ethane. On Earth, clathrates that contain methane are found in some polar and ocean sediments. On Titan, the surface pressure and temperature allow clathrates to form when liquid hydrocarbons come into contact with water ice, a main component of the moon's crust. These clathrates could remain stable as far down as several kilometres below the surface of Titan.

Lakes on Titan. Credit: NASA/JPL/USGS

"One of the interesting properties of clathrates is that they cause fractionation – in this case, they trap and split molecules into a mix of liquid and solid phases," adds Mousis. Because of this, astronomers have suggested that clathrates may be responsible for many unusual phenomena on Titan, including the depletion of the heavy noble gases in the moon's atmosphere, and variations in the moon's polar radius.

Titan's subsurface clathrate reservoirs would interact with and fractionate the liquid methane within the original underground hydrocarbon lake, slowly changing its composition. Eventually, subsurface lakes that had come into contact with the clathrate layer would mainly be composed of either propane or ethane, depending on the type of clathrate that had formed.

Importantly, this would continue up to Titan's surface. Lakes fed by these propane or ethane subsurface reservoirs would show the same kind of composition, whereas those fed by rainfall would be different and contain methane, nitrogen, and trace amounts of argon and carbon monoxide. "This means we would be able to look at the composition of the surface lakes and learn something about what is happening deep underground," says Mousis.

The Cassini Solstice mission, an extension of Cassini that runs until 2017, will give scientists a chance to explore Titan's surface lakes even more closely by performing an additional 54 close flybys of the Saturnian moon.

"Understanding Titan's hydrological cycle is one of the most important objectives of Cassini's extended mission," says ESA's Cassini-Huygens project scientist Nicolas Altobelli. "The changing seasons on Titan mean that soon we can again explore the lake-filled region at its north pole, and maybe spot seasonal phenomena we haven't seen before. This is crucial to getting a better understanding of what lies hidden beneath Titan's surface."

More information:

"Equilibrium composition between liquid and clathrate reservoirs on Titan" by O. Mousis et al. is published in the journal Icarus, Volume 239, 1 September 2014; doi: 10.1016/j.icarus.2014.05.032

The Cassini–Huygens mission is a cooperative project of NASA, ESA and the Italian Space Agency (ASI). Launched in 1997, Cassini arrived in the Saturn system in 2004 and is studying the ringed planet and its moons. The Huygens probe was released from the main spacecraft and, in 2005, parachuted through the atmosphere to the surface of Saturn's largest moon, Titan.

The spacecraft is designed for microgravity experiments, providing reception of new knowledge on the physics of weightlessness and the refinement of manufacturing processes of semiconductor materials, biomedical products with improved performance, as well as conducting biological and biotechnological research.

Foton-M4 landed

Total on board the satellite was installed 22 sets of scientific equipment, including biological animals: 5 geckos, fly Drosophila, the seeds of plants and micro organisms.

Mass of the satellite was 6840 kg, the mass of scientific equipment - up to 850 kg (600 kg lander inside and outside 250 kg). The average height of the orbit Foton-M4 was 575 km, which is higher than the average height of the orbit of the International Space Station.

Image above: InsideFoton-M4capsule with the variousexperimentalbox, in the center, the box oftheflies Drosophila.

Launch of spacecraft Foton-M4 held with launch pad number 31 Baikonur cosmodrome July 19, 2014.

On the state of biological animals aboard Foton-M4

After extraction of biological objects from the lander to carry out the initial evaluation, it was found that the fly Drosophila moved spaceflight well, successfully developed and bred. All geckos, unfortunately, died. Date of death and the conditions set by experts.

Scientific equipment with experiments prepared for transportation to the laboratory

Currently, scientific equipment with experiments prepared for transportation to the laboratory research institutes.

Massive stars end their life with a bang, exploding as supernovas and releasing massive amounts of energy and matter. What remains of the star is a small and extremely dense remnant: a neutron star or a black hole.

Neutron stars come in several flavours, depending on properties such as their ages, the strength of the magnetic field concealed beneath their surface, or the presence of other stars nearby. Some of the energetic processes taking place around neutron stars can be explored with X-ray telescopes, like ESA's XMM-Newton.

Neutron stars at odds

This image depicts two very different neutron stars that were observed in the same patch of the sky with XMM-Newton. The green and pink bubble dominating the image is Kesteven 79, the remnant of a supernova explosion located about 23,000 light-years away from us.

From the properties of the hot gas in Kesteven 79 and from its size, astronomers estimate that it is between 5000 and 7000 years old. Taking account of the time needed for light to travel to Earth, this means that the supernova that created it must have exploded almost 30,000 years ago. The explosion left behind a a young neutron star with a weak magnetic field, which can be seen as the blue spot at the centre of Kesteven 79.

Beneath it, a blue splotch indicates an entirely different beast: a neutron star boasting an extremely strong magnetic field, known as a magnetar. Astronomers discovered this magnetar, named 3XMM J185246.6+003317, in 2013 by looking at images that had been taken in 2008 and 2009. After the discovery, they looked at previous images of the same patch of the sky, taken before 2008, but did not find any trace of the magnetar. This suggests that the detection corresponded to an outburst of X-rays released by the magnetar, likely caused by a dramatic change in the structure of its magnetic field.

ESA's XMM-Newton

While the neutron star in the supernova remnant is relatively young, the magnetar is likely a million years old; the age difference means that it is very unlikely that the magnetar arose from the explosion that created Kesteven 79, but must have formed much earlier.

This false-colour image is a composite of 15 observations performed between 2004 and 2009 with the EPIC MOS camera on board XMM-Newton. The image combines data collected at energies from 0.3 to 1.2 keV (shown in red), 1.2 to 2 keV (shown in green) and 2 to 7 keV (shown in blue).